Organic electroluminescence elements (organic EL elements) have been used as self-luminous elements for image display devices, such displays, and for surface light sources. Such an organic EL element (organic light-emitting diode (OLED)) is generally prepared by stacking a transparent electrode serving as an anode, an organic layer, and a metal electrode serving as a cathode in this order on a transparent supporting substrate such as a glass substrate or a transparent plastic film. Thus, upon application of a voltage between the transparent electrode and the metal electrode, electron supplied from the cathode and holes supplied from the anode are recombined at the organic layer. Then, when an exciton generated by the recombination changes from an excited state to a ground state, EL emission occurs. Light of the EL emission goes through the transparent electrode, and then is extracted to the outside on the transparent supporting substrate side.
However, such an organic EL element has a problem that light generated at the organic layer cannot be extracted to the outside sufficiently. Specifically, there is a problem that a large proportion of light generated at the organic layer disappears as heat during repartition of multiple reflection in the element, or propagates inside the element and exits from end portions of the element, so that a sufficient external extraction efficiency cannot be achieved. To solve these problems, for example, Japanese Unexamined Patent Application Publication No. 2009-9861 (Patent Literature 1) discloses an organic EL element having a corrugated structure, the organic EL element comprising: a transparent supporting substrate; a cured resin layer which is stacked on the transparent supporting substrate and which has concavities and convexities formed on a surface thereof in a periodic arrangement; and a transparent electrode, an organic layer, and a metal electrode which are stacked in this order on the cured resin layer and formed into such shapes that a shape of the concavities and convexities formed on the surface of the cured resin layer is maintained.